Tracking accuracy is basically related to the reachable
bandwidth of the position control loop and can be directly
evaluated measuring the tracking error along reference
trajectories. This error is affected by axis friction, that
produces typical errors when the velocity sign is inverted
(often indicated as “quadrature glitches” or “inversion errors”)
and can reduce workpiece surface accuracy in finishing
operations. Several studies on friction modeling have tackled
those issues, with the goal of adopting model-based control
schemes that forecast the motor torque required to
compensate friction.
In order to reach a high material removal capability, a
machine must withstand process forces with limited
displacements at the tool and the work piece. A tool cutter
undergoing large displacements produces a waved machined
surface, that, when cut by the subsequent cutter, will provoke
oscillating forces. This regenerative process can became
unstable, as studied by the classic chatter theory in metal
cutting operations [6]. Stability lobes diagrams can be
computed basing on the tool – work piece dynamic
compliance and cutting process parameters, indicating the
system vibration modes that mainly limit the material removal
capability.